The present invention relates to a direct modulation FM data receiver which is suitable for fabricating as an integrated circuit (IC) and can be used as a paging receiver.
There have been many proposals, see for example British Patent Specification No. 1,530,602, for what is termed "direct conversion" or "zero i.f." receiver structures which were intended to be fabricated as an IC and may constitute an alternative to the conventional superheterodyne receiver. Because the frequency of the output of a direct conversion receiver is the same for positive and negative displacements of the modulating signal from the carrier frequency, it is necessary to provide a pair of front end mixers which provide quadrature outputs and considerable demodulator complexity in order to distinguish between the positive and negative cases.